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use std::borrow::Cow;
// check that Cow<'a, str> implements addition
#[test]
fn check_cow_add_cow() {
let borrowed1 = Cow::Borrowed("Hello, ");
let borrowed2 = Cow::Borrowed("World!");
let borrow_empty = Cow::Borrowed("");
let owned1: Cow<'_, str> = Cow::Owned(String::from("Hi, "));
let owned2: Cow<'_, str> = Cow::Owned(String::from("Rustaceans!"));
let owned_empty: Cow<'_, str> = Cow::Owned(String::new());
assert_eq!("Hello, World!", borrowed1.clone() + borrowed2.clone());
assert_eq!("Hello, Rustaceans!", borrowed1.clone() + owned2.clone());
assert_eq!("Hi, World!", owned1.clone() + borrowed2.clone());
assert_eq!("Hi, Rustaceans!", owned1.clone() + owned2.clone());
if let Cow::Owned(_) = borrowed1.clone() + borrow_empty.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = borrow_empty.clone() + borrowed1.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = borrowed1.clone() + owned_empty.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = owned_empty.clone() + borrowed1.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
}
#[test]
fn check_cow_add_str() {
let borrowed = Cow::Borrowed("Hello, ");
let borrow_empty = Cow::Borrowed("");
let owned: Cow<'_, str> = Cow::Owned(String::from("Hi, "));
let owned_empty: Cow<'_, str> = Cow::Owned(String::new());
assert_eq!("Hello, World!", borrowed.clone() + "World!");
assert_eq!("Hi, World!", owned.clone() + "World!");
if let Cow::Owned(_) = borrowed.clone() + "" {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = borrow_empty.clone() + "Hello, " {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = owned_empty.clone() + "Hello, " {
panic!("Adding empty strings to a borrow should note allocate");
}
}
#[test]
fn check_cow_add_assign_cow() {
let mut borrowed1 = Cow::Borrowed("Hello, ");
let borrowed2 = Cow::Borrowed("World!");
let borrow_empty = Cow::Borrowed("");
let mut owned1: Cow<'_, str> = Cow::Owned(String::from("Hi, "));
let owned2: Cow<'_, str> = Cow::Owned(String::from("Rustaceans!"));
let owned_empty: Cow<'_, str> = Cow::Owned(String::new());
let mut s = borrowed1.clone();
s += borrow_empty.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = borrow_empty.clone();
s += borrowed1.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = borrowed1.clone();
s += owned_empty.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = owned_empty.clone();
s += borrowed1.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
owned1 += borrowed2;
borrowed1 += owned2;
assert_eq!("Hi, World!", owned1);
assert_eq!("Hello, Rustaceans!", borrowed1);
}
#[test]
fn check_cow_add_assign_str() {
let mut borrowed = Cow::Borrowed("Hello, ");
let borrow_empty = Cow::Borrowed("");
let mut owned: Cow<'_, str> = Cow::Owned(String::from("Hi, "));
let owned_empty: Cow<'_, str> = Cow::Owned(String::new());
let mut s = borrowed.clone();
s += "";
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = borrow_empty.clone();
s += "World!";
assert_eq!("World!", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = owned_empty.clone();
s += "World!";
assert_eq!("World!", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
owned += "World!";
borrowed += "World!";
assert_eq!("Hi, World!", owned);
assert_eq!("Hello, World!", borrowed);
}
#[test]
fn check_cow_clone_from() {
let mut c1: Cow<'_, str> = Cow::Owned(String::with_capacity(25));
let s: String = "hi".to_string();
assert!(s.capacity() < 25);
let c2: Cow<'_, str> = Cow::Owned(s);
c1.clone_from(&c2);
assert!(c1.into_owned().capacity() >= 25);
let mut c3: Cow<'_, str> = Cow::Borrowed("bye");
c3.clone_from(&c2);
assert_eq!(c2, c3);
}
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